Persistence Methods like Source IP, Cookie etc provide a way to make sure that incoming connections are sent to the same server that handled the initial request. For example, for Source IP based persistence, when a connection comes in and if there is a persistence table entry for that client IP on the F5, the connection will be sent to the same server that handled the request within a specific time out threshold.

A pool consists of the following:

Pool Members

Load Balancing Method

Monitor

A Pool consists of multiple pool members. A pool member is an “IP address + Port”. A node is an IP address.

Load Balancing Methods will help the F5 to balance traffic across the pool members in the pool.

Monitor is utilized to check the health of the pool member. Simple health checks can be ICMP ping or TCP socket check on specific ports. A good practice is to make sure that the timeout period is [(3*Frequency) + 1]. So, if frequency of monitor checks is 5 seconds, timeout would be 16 seconds and this means 3 consecutive failures will result in the pool member being marked down.